Sheet feeding apparatus



July 14, 1970 PHLEPS ETAL SHEET FEEDING APPARATUS Filed April 15, 1968 Fig.2

RH mu 5 m I R. PNR m m mu N SU P 8 N E .1 MWM N OHUH KGH 9 M a 5 2 6 2 M/am f- J/M F United States Patent 3,520,533 SHEET FEEDING APPARATUS Konrad Phleps, Deisenhofen, and Giinter Schnall and Hermann Ullrich, Munich, Germany, assignors to Agfa- Gevaert Aktiengesellschaft, Leverkusen, Germany Filed Apr. 15, 1968, Ser. No. 721,523 Claims priority, application Germany, Apr. 15, 1967, A 55,461 Int. Cl. B65h N08 US. Cl. 271-39 12 Claims ABSTRACT OF THE DISCLOSURE A sheet feeding apparatus wherein the rear portion of the feed table is tiltably supported between two upright walls of the frame. The front portion of the table is biased upwardly by a spring so as to maintain the topmost sheet of the stack on the table in abutment with two intermittently driven feed rolls mounted in the frame at a level above the feed table. The frame supports a stationary front stop which abuts against the front face of the stack and two corner separators which are slightly spaced from the top face of the topmost sheet. The corner separators are mounted on the frame by way of two side rails which are adjacent to the side faces of the stack and at least one of which is movable toward or away from the other side rail.

BACKGROUND OF INVENTION The present invention relates to sheet feeding apparatus for use in or with duplicating, copying or other sheet consuming or sheet processing machines. More particularly, the invention relates to improvements in sheet feeding apparatus wherein the height of the stack is reduced by removal of topmost sheets.

Many types of sheet feeding apparatus are known in the art. As a rule, such apparatus comprise corner separators which are adjacent to the front corners of the topmost sheet and cooperate with the feed to insure that only one sheet is being removed at a time. The corner separators normally abut against the front comer of the topmost sheet and, in order to insure that they remain in abutment with successive topmost sheets, it is necessary to provide rather complicated devices which move the corner separators at a rate corresponding to the rate at which the height of the stack diminishes. Reference may be had, for example, to Fengler et al. Pat. No. 3,278,181. Furthermore, the corner separators must be mounted in such a way that they can be moved toward or away from each other in order to properly engage the corners of relatively narrow or relatively wide sheets. Additional problems arise in conventional sheet feeding apparatus if the quality (particularly the thickness) of sheets in successive stacks is not the same; it is then necessary to employ exchangeable weights, exchangeable feed members or other parts which can compensate for such changes in sheet thickness.

SUMMARY OF THE INVENTION It is an object of our invention to provide a simple, inexpensive, compact and versatile sheet feeding apparatus which can accommodate and feed large, small, wide, narrow, long, short, thick or thin sheets with equal facility and wherein the level of the corner separators need not be changed when the height of the stack diminishes.

Another object of the invention is to provide a sheet feeding apparatus wherein the corner separators can be adjusted, when necessary, in automatic response to adjustment of other parts of the apparatus which must change their positions when a relatively wide stack is followed by a narrower stack or vice versa.

3,520,533 Patented July 14, 1970 A further object of the invention is to provide a sheet feeding apparatus wherein the distance between the side rails can be regulated in a simple and time-saving manner.

An additional object of the invention is to provide a sheet feeding apparatus wherein the sheets are being removed from the top of the stack and which can operate properly without weights which are normally used on top of the stack in conventional sheet feeding apparatus.

An ancillary object of the invention is to provide a novel and improved mounting for the feed table in a sheet feeding apparatus.

Another object of the invention is to provide a sheet feeding apparatus wherein the corner separators can be rigidly affixed to the side rails and wherein the front stop can be fixedly secured to the frame.

The improved sheet feeding apparatus comprises a frame supporting a feed table which is arranged to carry a stack of sheets, an intermittently operated feed preferably comprising two coaxial feed rolls mounted in the frame at a level above the front portion of the feed table and arranged to advance the topmost sheet beyond the front face of the stack so that the thus dislodged sheet may be engaged by two continuously driven advancing rollers or the like to be moved into a duplicating, copying or other sheet consuming machine, means for urging at least a portion of the feed table upwardly to maintain the topmost sheet of the stack in engagement with the feed, a front stop fixed to the frame and disposed in front of the feed table to abut against the front face of the stack, and a pair of stationary corner separators supported by the frame and each adjacent to one front corner of the topmost sheet of the stack on the feed table. The corner separators are preferably rigid with two side rails each of which is adjacent to one side face of the stack on the feed table and at least one of which is adjustable in a direction toward or away from the other side rail. The rear portion of the feed table is preferably tiltable about a longitudinally extending horizontal axis and the means for moving the front portion of the table upwardly preferably comprises a spring which biases the topmost sheet of the stack against the feed. The corner separators comprise top portions which overlie the top face of the topmost sheet but are spaced therefrom by a relatively small distance, preferably in the range of 0.1 to 0.5 millimeter.

The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The improved sheet feeding appparatus itself, however, both as to its construction and its mode of operation, together with additional features and advantages thereof, will be best understood upon perusal of the following detailed description of a specific embodiment with reference to the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a top plan view of a sheet feeding apparatus which embodies the invention, certain parts of the apparatus being shown in section; and

FIG. 2 is a longitudinal vertical sectional view as seen in the direction of arrows from the line IIII of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT The sheet feeding apparatus which is shown in FIGS. 1 and 2 comprises a frame including two spaced parallel upright supporting walls 1, 2. These walls support the end portions of a transversely extending horizontal shaft 3 which drives two elastic feed rolls 6, 7 secured thereto by screws 4 and 5. One end portion of the shaft 3 carries a driver gear 8 which is coupled thereto by a helical choking spring 9 capable of transmitting torque when the gear 8 rotates in one direction but permitting the gear to rotate with reference to the shaft when the gear rotates in the opposite direction. The gear 8 meshes with a reciprocable rack 8a so that, when the rack is in motion, the shaft 3 and feed rolls 6, 7 rotate intermittently in a counterclockwise direction, as view in FIG. 1. The spring 9 can be replaced by another suitable one-way clutch which causes the gear 8 to transmit to the shaft 3 torque only when the gear rotates in one direction.

The walls 1, 2 of the frame further support a second shaft 10 which is parallel to and is located behind the shaft 3, as considered in the direction of feed (see the arrow A). The shaft 10 extends with clearance through cutouts or recesses 11a, 11b provided in the rear portion of a feed table 11 located between the walls 1 and 2. The rear portion of the table 11 is suspended on the shaft 10 by a bracket 12 which is located substantially midway between the walls 1 and 2. The connection between the table 11 and shaft 10 by means of the bracket 12 is preferably such that the table can tilt slightly about a horizontal axis which is parallel to and extends midway between the walls 1 and 2. The cutouts 11a, 11b are large enough to permit some tilting of the rear portion of the table 11 with reference to the shaft 10. The front portion of the table 11 is engaged from below by a helical lifting spring 13 having a lowermost convolution secured to a stationary retainer 13a. The spring 13 operates substantially midway between the lateral edges of the table 11 and biases the latter upwardly toward the feed rolls 6 and 7. The table supports a stack 14 of paper sheets and the uppermost sheet of this stack is biased by spring 13 against the feed rolls 6 and 7. It will be seen that the bracket 12 and the rolls 6, 7 form a three-point locating unit which determines the angular position of the feed table 11 irrespective of the height of the stack 14. If the height of the stack is reduced, the spring 13 moves the front portion of the table 11 to a higher level so that the topmost sheet of the stack invariably abuts against the rolls 6 and 7. Furthermore, and since the rear portion of the table 11 has some freedom of tilting movement with reference to the shaft 10, the spring 13 invariably insures that the topmost sheet of the stack 14 bears against both feed rolls with equal force. This is important because, when the gear 8 drives the shaft 3 in a counterclockwise direction, as viewed in FIG. 1, friction between the topmost sheet of the stack 14 and the roll 6 is the same as that between the topmost sheet and the roll 7, irrespective of the height of the stack.

The walls 1 and 2 further support a transversely extending fixed front stop 15 which is located in front of the shaft 3 and engages the front face of the stack 14 on the feed table 11. The end portions of the front stop 15 are bent over to form two lugs 15a which are screwed or riveted to the walls 1 and 2. These walls 1, 2 also support two side rails 16, 17 which engage the adjoining side faces of the stack 14 on the feed table. The side rail 16 is provided with laterally outwardly extending projections or pins 20, 21 which are received in holes provided in the wall 1 and are releasably retained in such holes by screws 22, 23 or similar fasteners. The other side rail 17 has two laterally outwardly extending guide pins 24, 25 which extend through and beyond holes provided therefor in the wall 2 but are not fastened to this wall. The means for adjusting the distance between the side rails 16, 17 comprises a spindle 26 which is anchored in the side rail 17 and meshes with a spindle nut 27 which is rotatably mounted in the wall 2. By rotating the nut 27, the operator can move the side rail 17 nearer to or further away from the side rail 16 to insure that the stack 14 is properly oriented on the top face of the feed table 11. The side rail 16 is also adjustable in a direction toward or away from the side rail 17.

Two corner separators 18, 19 are respectively secured to the side rails 16, 17 adjacent to the respective ends of the front stop 15. These corner separators have front portions which are in abutment with the front face of the stack 14 adjacent to the top part of the stack and top portions or lips which overlie the respective front corners of the topmost sheet but are spaced therefrom by a distance of between 0.1-0.5 millimeter, preferably about 0.3 millimeter. Thus, the distance between the level of the lowermost portions of peripheral surfaces on the rolls 6, 7 and the level of undersides of the lips of corner separators 18, 19 is preferably about 0.3 millimeter.

The bottom edges 16a, 16b and 17a, 17b of the side rails 16, 17 are spaced from the top face of the table 11 by a distance which sutfices to insure that the table can tilt with reference to the shaft 10 in order to enable the spring 13 to bias the topmost sheet of the stack 14 against both feed rolls with an equal force. However, and to insure that both lateral faces of the entire stack 14 are properly guided regardless of the height of the stack, the side rails 16, 17 are respectively provided with downwardly extending projections or skirts 16c, 16d, 16e and 17c, 17d, 17e which extend through lateral recesses or cutouts 11c, 11d, lle and 117, 11g, 11h of the feed table.

The walls 1, 2 further support two transversely extending horizontal shafts 30a, 31a which carry advancing rollers 30, 31 of rubber or the like. These rollers are driven in opposite directions (see the arrows in FIG. 2) by mating spur gears 28, 29 one of which is rotated in synchronism with operation of a consuming machine, e.g., a duplicator or the like, which receives a succession of sheets from the stack 14. The rollers 30, 31 are preferably driven at a constant speed.

An important advantage of our sheet feeding apparatus is that the level (vertical position) of the corner separators 18, 19 need not be changed in order to compensate for changes in the height of the stack, regardless of whether such height changes because a fresh supply of sheets is being placed onto the table 11 or because the height of the stack diminishes in response to withdrawal of successive topmost sheets. This is due to the fact that the feed rolls 6, 7 cooperate with the spring 13 to properly locate the front corners of the topmost sheet with reference to the corner separators 18, 19 irrespective of the height of the stack. Furthermore, and since the table 11 is biased upwardly by the spring 13, it is not necessary to employ weights which are needed in many presently known sheet feeding apparatus. The apparatus of our invention can be used for feeding of wide, narrow, short, long, thick or thin sheets, irrespective of whether the sheets in a stack are or are not of the same thickness. All that is needed to convert the apparatus for feeding of wider or narrower sheets is to move the side rail 17 toward or away from the side rail 16 and/or to eventually change the position of the side rail 16 with reference to the adjoining wall 1. The fact that the topmost sheet of the stack might bear against the feed rolls 6, 7 with a greater or lesser force does not influence the function of corner separators 18, 19 because the lips of these corner separators invariably remain at a chosen distance from the top face of the topmost sheet.

The characteristics of the spring 13 are preferably such that its bias against the topmost sheet changes very little irrespective of changes in the height of the stack, i.e., in response to changes in the distance between the front portion of the feed table 11 and the feed rolls 6, 7. In other words, the characteristic of spring 13 is selected in such a way that its bias decreases substantially proportionally with reduction of the weight of the stack 14 on the feed table 11. Therefore, the pressure between the uppermost sheet and the feed rolls 6 and 7 is the same, or nearly the same, irrespective of the height of the stack 14. The pressure with which the uppermost sheet bears against the rolls 6 and 7 corresponds to the difference between the force produced by the spring 13 and the combined weight of the feed table 11 and stack 14. Such selection of the spring characteristic is important and desirable, especially if the feed table 11 is to accommodate a substantial number of sheets so that the weight of a stack may equal or even exceed the weight of the feed table.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features which fairly constitute essential characteristics of the generic and specific aspects of our contribution to the art and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the claims.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims.

1. A sheet feeding apparatus for use in or with duplicating, copying or like machines, comprising a feed table arranged to support a stack of sheets thereon; an intermittently operated feed located at a fixed level above the table and arranged to advance the topmost sheet of the stack forwardly beyond the front face of the remainder of the stack; means for urging at least a portion of said table upwardly so as to maintain the topmost sheet of the stack in abutment with said feed; a fixed front stop disposed in front of said table to abut against the front face of the stack thereon; and a pair of fixed corner separators each adjacent to one front corner of the topmost sheet of the stack.

2. A sheet feeding apparatus as defined in claim 1, wherein said corner separators have portions located at a level above and slightly spaced from the top face of the topmost sheet of the stack on said table.

3. A sheet feeding apparatus as defined in claim 2, wherein the distance between the top face of that sheet which abuts against said feed and said portions of said corner separators is in the range of 0.1 to 0.5 millimeter.

4. A sheet feeding apparatus as defined in claim 1, further comprising supporting means for tiltably supporting said table, said urging means comprising means for biasing said table upwardly against said feed.

5. A sheet feeding apparatus as defined in claim 4, wherein said biasing means comprises a spring which stores energy when the stack is of greater height and dissipates such energy to move a portion of the table upwardly when the height of the stack decreases, the characteristic of said spring being such that the pressure between the topmost sheet of the stack and said feed remains substantially constant irrespective of the height of the stack on said table.

6. A sheet feeding apparatus as defined in claim 4, wherein said supporting means is arranged to support a rear portion of the table and wherein said feed comprises a pair of spaced feed rolls located above the front portion of said table, said biasing means comprising spring means disposed below said front portion of the table to bias the latter upwardly so that the topmost sheet of the stack abuts against both feed rolls.

7. A sheet feeding apparatus as defined in claim 1, further comprising a frame supporting said feed, said front stop and said corner separators.

8. A sheet feeding apparatus as defined in claim 7, further comprising a pair of side rails each adjacent to one side face of the stack on said table and each supported by said frame, each of said corner separators being affixed to one of said side rails.

9. A sheet feeding apparatus as defined in claim 1, further comprising a frame for said front stop, said corner separators and said feed, supporting means carried by said frame and tiltably supporting said table, and a pair of side rails mounted in said frame adjacent to the side faces of the stack on said table and sufficiently spaced from said table to permit tilting of the table therebetween.

10. A sheet feeding apparatus as defined in claim 9, wherein at least one of said side rails is movable toward or away from the other side rail.

11. A sheet feeding apparatus as defined in claim 9, wherein said side rails comprise downwardly projecting extensions passing through recesses provided therefor in said table.

12. A sheet feeding apparatus as defined in claim 1, further comprising a frame supporting said feed, said front stop and said corner separators, and a pair of side rails each mounted in said frame and each adjacent to one side face of the stack on said table, and adjusting means for moving one of said side rails toward or away from the other side rail.

References Cited UNITED STATES PATENTS 3,029,074 4/1962 Springer 271-52 3,046,007 7/ 1962 Stephenson 271-61 3,260,521 7/1966 Moxness 271-39 3,301,551 12/1967 Cassano 271-39 3,348,838 10/1967 Springer 27162 RICHARD AEGERTER, Primary Examiner 

